Earnings Per Share (EPS) And Dividends (Basic And Diluted Earnings Per Share Computation) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Net Income	$ (177)	$ 451	$ 471	$ 899
Weighted Average Common Shares Outstanding, Basic (shares)	504	504	504	504
Effect of Stock Based Compensation Awards, Basic (shares)	0	0	0	0
Total Shares, Basic (shares)	504	504	504	504
Net Income, Basic (dollars per share)	$ (0.35)	$ 0.89	$ 0.94	$ 1.78
Weighted Average Common Shares Outstanding, Diluted (shares)	504	504	504	504
Effect of Stock Based Compensation Awards, Diluted (shares)	0	3	3	3
Total Shares, Diluted (shares)	504	507	507	507
Net Income, Diluted (dollars per share)	$ (0.35)	$ 0.89	$ 0.93	$ 1.77